ABSTRACT
Three major proteases, elastase B (LasB), protease IV (PIV), and elastase A (LasA) expressed in Pseudomonas aeruginosa play important roles in infections and pathogeneses. These are activated by a proteolytic cascade initiated by the activation of LasB. In this study, we investigated whether LasB could be inhibited using its propeptide (LasBpp). Although LasA and PIV were inhibited by their propeptides, LasB was not inhibited by purified LasBpp because LasB degraded LasBpp. To address this problem, mutant LasBpp variants were constructed to obtain a mutant LasBpp resistant to LasB degradation. A C-terminal deletion series of LasBpp was tested in vivo, and two positive candidates, T2 and T2-1, were selected. However, both caused growth retardation and were unstably expressed in vivo. Since deleting the C-terminal end of LasBpp significantly affected its stable expression, substitution mutations were introduced at the two amino acids near the truncation site of T2-1. The resulting mutants, LasBppE172D, LasBppG173A, and LasBppE172DG173A, significantly diminished LasB activity when overexpressed in vivo and were stably expressed in MW1, a quorum sensing mutant that does not produce LasB. In vitro analysis showed that purified LasBppE172DG173A inhibited LasB activity to a small extent. Summarizing, C-terminal modification of LasBpp profoundly affected the stable expression of LasBpp, and little enhanced the ability of LasBpp to resist degradation by LasB.
Subject(s)
Metalloendopeptidases , Pseudomonas aeruginosa , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Metalloendopeptidases/chemistry , Metalloendopeptidases/genetics , Metalloendopeptidases/metabolism , Pancreatic Elastase/genetics , Pancreatic Elastase/metabolism , Peptides/antagonists & inhibitors , Peptides/metabolism , Pseudomonas aeruginosa/genetics , Pseudomonas aeruginosa/metabolism , Quorum Sensing/geneticsABSTRACT
Central venous catheterization is associated with a large number of complications, such as pneumothorax, hydrothorax, hemothorax, phlebothrombosis, pericardial tamponade, air embolism, aberrant placement and line sepsis. There are many case reports of the extravasation of various central venous catheter fluids, including the intravenous fluids, total parenteral nutrition and chemotherapeutic agents into the pleural cavity and mediastinum. These have led to hydrothorax, hydromediastinum and pericardial effusions. We report a case of the extravasation of intravenous contrast into the pleural cavity after dynamic CT through a left subclavian catheter.
ABSTRACT
Myocardial bridge is a congenital anomaly characterized by narrowing of some of the epicardial coronary arterial segments running in the myocardium during systole. Occasionally, the compression of a coronary artery by a myocardial bridge can be associated with the clinical manifestations of myocardial ischemia, and might even trigger a myocardial infarction or malignant ventricular arrhythmias. We report a case of ventricular fibrillation due to coronary spasm at the site of myocardial bridge. A 56-year-old man who had suffered from bronchial asthma was given remifentanil combined with sevoflurane in general anesthesia for endoscopic sinus surgery. During the surgery, ventricular fibrillation occurred following coronary spasm with bradycardia, hypotension, bronchospasm. we found myocardial bridge that coincided with an area of coronary spasm after coronary angiography.